Gitweb:     http://git.kernel.org/linus/dc8f6d8936eb244eea452af689df5ee19e635206
Commit:     dc8f6d8936eb244eea452af689df5ee19e635206
Parent:     22c963addcf426bef97a43f6e601f985f8082ed5
Author:     Frederic Weisbecker <fweisbec@gmail.com>
AuthorDate: Tue Apr 14 05:34:25 2009 +0200
Committer:  Frederic Weisbecker <fweisbec@gmail.com>
CommitDate: Mon Sep 14 07:18:04 2009 +0200

    kill-the-BKL/reiserfs: only acquire the write lock once in reiserfs_dirty_inode
    
    Impact: fix a deadlock
    
    reiserfs_dirty_inode() is the super_operations::dirty_inode() callback
    of reiserfs. It can be called from different contexts where the write
    lock can be already held.
    
    But this function also grab the write lock (possibly recursively).
    Subsequent release of the lock before sleep will actually not release
    the lock if the caller of mark_inode_dirty() (which in turn calls
    reiserfs_dirty_inode()) already owns the lock.
    
    A typical case:
    
    reiserfs_write_end() {
    	acquire_write_lock()
    	mark_inode_dirty() {
    		reiserfs_dirty_inode() {
    			reacquire_write_lock() {
    				journal_begin() {
    					do_journal_begin_r() {
    						/*
    						 * fail to release, still
    						 * one depth of lock
    						 */
    						release_write_lock()
    						reiserfs_wait_on_write_block() {
    							wait_event()
    
    The event is usually provided by something which needs the write lock but
    it hasn't been released.
    
    We use reiserfs_write_lock_once() here to ensure we only grab the
    write lock in one level.
    
    Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: Alessio Igor Bogani <abogani@texware.it>
    Cc: Jeff Mahoney <jeffm@suse.com>
    Cc: Chris Mason <chris.mason@oracle.com>
    LKML-Reference: <1239680065-25013-4-git-send-email-fweisbec@gmail.com>
    Signed-off-by: Ingo Molnar <mingo@elte.hu>
---
 fs/reiserfs/super.c |   15 +++++++++------
 1 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/fs/reiserfs/super.c b/fs/reiserfs/super.c
index e1cfb80..58727b5 100644
--- a/fs/reiserfs/super.c
+++ b/fs/reiserfs/super.c
@@ -554,25 +554,28 @@ static void reiserfs_dirty_inode(struct inode *inode)
 	struct reiserfs_transaction_handle th;
 
 	int err = 0;
+	int lock_depth;
+
 	if (inode->i_sb->s_flags & MS_RDONLY) {
 		reiserfs_warning(inode->i_sb, "clm-6006",
 				 "writing inode %lu on readonly FS",
 				 inode->i_ino);
 		return;
 	}
-	reiserfs_write_lock(inode->i_sb);
+	lock_depth = reiserfs_write_lock_once(inode->i_sb);
 
 	/* this is really only used for atime updates, so they don't have
 	 ** to be included in O_SYNC or fsync
 	 */
 	err = journal_begin(&th, inode->i_sb, 1);
-	if (err) {
-		reiserfs_write_unlock(inode->i_sb);
-		return;
-	}
+	if (err)
+		goto out;
+
 	reiserfs_update_sd(&th, inode);
 	journal_end(&th, inode->i_sb, 1);
-	reiserfs_write_unlock(inode->i_sb);
+
+out:
+	reiserfs_write_unlock_once(inode->i_sb, lock_depth);
 }
 
 #ifdef CONFIG_QUOTA
--
To unsubscribe from this list: send the line "unsubscribe git-commits-head" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html